CN112403873B - Stack ultrasonic transducer - Google Patents
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- 239000010410 layer Substances 0.000 claims description 204
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- 230000005284 excitation Effects 0.000 claims description 21
- 239000002131 composite material Substances 0.000 claims description 10
- 239000000919 ceramic Substances 0.000 claims description 9
- 239000013078 crystal Substances 0.000 claims description 9
- 230000005404 monopole Effects 0.000 claims description 9
- 230000003014 reinforcing effect Effects 0.000 claims description 9
- 239000002356 single layer Substances 0.000 claims description 6
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- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
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- B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
- B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
- B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
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- B06B2201/50—Application to a particular transducer type
- B06B2201/55—Piezoelectric transducer
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
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- B06B2201/76—Medical, dental
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Abstract
The application discloses a stacked ultrasonic transducer. The stacked ultrasonic transducer comprises a back lining layer, a low-frequency piezoelectric layer, an insulating layer and a combined layer which are sequentially arranged from bottom to top; the combined layer includes: the piezoelectric device comprises a low-frequency matching layer, a medium-frequency piezoelectric layer, a high-frequency piezoelectric layer and a high-frequency matching layer; a low-frequency matching layer is arranged on the upper surface of the insulating layer; etching the upper surface of the low-frequency matching layer downwards to the upper surface of the insulating layer to form a through cavity; the middle-frequency piezoelectric layer, the high-frequency piezoelectric layer and the high-frequency matching layer are sequentially arranged in the penetrating cavity from bottom to top. Each piezoelectric layer of the stacked ultrasonic transducer can be excited to generate ultrasonic waves with different frequencies, and the ultrasonic waves generated by the piezoelectric layers are spatially superposed to generate unipolar ultrasonic pulses, so that the occupied area is reduced while the imaging quality is improved.
Description
Technical Field
The invention relates to the technical field of medical ultrasonic detection instruments, in particular to a stacked ultrasonic transducer.
Background
The ultrasonic transducer based on the piezoelectric material has the advantages of mature technology, low cost, real-time imaging and the like, and is widely applied to the field of medical ultrasonic detection. Conventional PZT-based single frequency ultrasonic transducers typically achieve a relative bandwidth of-6 dB of 60% with a transmission waveform length of approximately 2-3 cycles. In order to improve the bandwidth of the ultrasonic transducer and improve the ultrasonic waveform, the ultrasonic transducer based on the piezoelectric composite material is developed, the-6 dB relative bandwidth of the ultrasonic transducer is close to 100%, the length of the transmission waveform is within 2 periods, and the quality of the ultrasonic image is improved to a greater extent. To further improve the quality of the ultrasound image, many other types of ultrasound detection technologies are developed, such as photoacoustic imaging technology, capacitive micromachined ultrasound transducer technology, and the like. The novel ultrasonic imaging modes can obtain higher resolution and better image quality, but the hardware equipment required by the modes is expensive, the equipment is complex, and the technical process is not mature.
In cavitation-based ultrasound therapy, short acoustic pulses within 2 cycles can produce more accurate tissue ablation, with smaller ultrasound lengths favoring accurate tissue ablation. The transmitted ultrasonic waves excited by the traditional ultrasonic transducer are difficult to reach 1-2 cycle lengths, and are generally used for detection and not used for emission even if the transmitted ultrasonic waves can be reached.
To further reduce the transmitted ultrasound length of a PZT material based transducer and improve the quality of the ultrasound image, a multi-frequency synthesis technique may be used to synthesize a single-pole ultrasound pulse. The most typical example is to use a plurality of single frequency ultrasonic transducers spatially arranged in a spherical or hemispherical shape so as to synthesize a unipolar ultrasonic pulse at the center of the sphere. The mode can synthesize unipolar ultrasonic pulses with excellent waveforms, but the overall radius of the plurality of single-frequency ultrasonic transducers reaches the decimeter level, so that the occupied area is large and the practical application is not facilitated.
Therefore, the existing scheme for generating the unipolar ultrasonic pulse to improve the imaging quality has the problem of large occupied area.
Disclosure of Invention
The invention aims to provide a stacked ultrasonic transducer, which can enable ultrasonic waves generated by each piezoelectric layer to be spatially overlapped to generate a unipolar ultrasonic pulse so as to improve the imaging quality and reduce the occupied area.
In order to achieve the purpose, the invention provides the following scheme:
a stack ultrasonic transducer comprises a back lining layer, a low-frequency piezoelectric layer, an insulating layer and a combined layer which are arranged from bottom to top in sequence; the combined layer includes: the piezoelectric device comprises a low-frequency matching layer, a medium-frequency piezoelectric layer, a high-frequency piezoelectric layer and a high-frequency matching layer;
the upper surface of the insulating layer is provided with the low-frequency matching layer; etching the upper surface of the low-frequency matching layer downwards to the upper surface of the insulating layer to form a through cavity; the medium-frequency piezoelectric layer, the high-frequency piezoelectric layer and the high-frequency matching layer are sequentially arranged in the penetrating cavity from bottom to top;
the low-frequency piezoelectric layer is used for receiving a low-frequency excitation signal and generating low-frequency ultrasonic waves; the medium-frequency piezoelectric layer is used for receiving medium-frequency excitation signals and generating medium-frequency ultrasonic waves; the high-frequency piezoelectric layer is used for receiving a high-frequency excitation signal and generating high-frequency ultrasonic waves;
the low-frequency matching layer is used for reinforcing the forward wave of the low-frequency ultrasonic wave; the high-frequency matching layer is used for reinforcing the forward wave of the high-frequency ultrasonic wave; the high-layer matching layer and the high-frequency piezoelectric layer form a medium-frequency matching layer, and the medium-frequency matching layer is used for reinforcing the forward wave of the medium-frequency ultrasonic wave; the forward wave is an ultrasonic wave transmitted from the backing layer to the high-frequency matching layer;
the back lining layer is used for attenuating the back waves of the low-frequency ultrasonic waves, the back waves of the medium-frequency ultrasonic waves and the back waves of the high-frequency ultrasonic waves; the backward wave is a backward wave of the forward wave;
the forward wave of the low-frequency ultrasonic wave, the forward wave of the medium-frequency ultrasonic wave and the forward wave of the high-frequency ultrasonic wave are superposed to form a monopole ultrasonic wave.
Optionally, the acoustic impedances of the low frequency piezoelectric layer, the medium frequency piezoelectric layer and the high frequency piezoelectric layer are the same.
Optionally, a ratio of the acoustic impedance of the backing layer to the acoustic impedance of the low frequency piezoelectric layer is in a range of 0.6:1 to 1.2: 1.
Optionally, the acoustic impedance of the insulating layer is 0.1 to 1.5 times the acoustic impedance of the low frequency piezoelectric layer.
Optionally, the thickness of the insulating layer is 0.01 to 3 times the wavelength of the high-frequency ultrasonic wave.
Optionally, the material of the low-frequency piezoelectric layer is piezoelectric ceramic, piezoelectric single crystal and/or piezoelectric composite material; the medium-frequency piezoelectric layer is made of piezoelectric ceramics, piezoelectric single crystals and/or piezoelectric composite materials; the material of the high-frequency piezoelectric layer is piezoelectric ceramic, piezoelectric single crystal and/or piezoelectric composite material.
Optionally, the center frequency of the low-frequency ultrasonic wave is 1MHz-10 MHz; the central frequency of the medium-frequency ultrasonic wave is 2MHz-40MHz, and the central frequency of the medium-frequency ultrasonic wave is 2-4 times of the central frequency of the low-frequency ultrasonic wave; the center frequency of the high-frequency ultrasonic wave is 4MHz-100MHz, and the center frequency of the high-frequency ultrasonic wave is 2-4 times of the center frequency of the medium-frequency ultrasonic wave.
Optionally, the low-frequency matching layer is a single-layer structure made of a single material or a multi-layer structure made of multiple different materials; the high-frequency matching layer is of a single-layer structure formed by adopting a single material or a multi-layer structure formed by adopting a plurality of different materials.
Optionally, the thickness of the low-frequency matching layer is 0.1-0.5 times of the wavelength of the low-frequency matching ultrasonic wave; the low-frequency matching ultrasonic wave is the ultrasonic wave when the low-frequency ultrasonic wave is transmitted to the low-frequency matching layer;
the thickness of the high-frequency matching layer is 0.1-0.5 times of the wavelength of the high-frequency matching ultrasonic wave; the high-frequency matching ultrasonic wave is the ultrasonic wave when the high-frequency ultrasonic wave is transmitted to the high-frequency matching layer.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention discloses a stacked ultrasonic transducer, which comprises a back lining layer, a low-frequency piezoelectric layer, an insulating layer and a combined layer which are sequentially arranged from bottom to top; the combined layer includes: the piezoelectric device comprises a low-frequency matching layer, a medium-frequency piezoelectric layer, a high-frequency piezoelectric layer and a high-frequency matching layer; a low-frequency matching layer is arranged on the upper surface of the insulating layer; etching the upper surface of the low-frequency matching layer downwards to the upper surface of the insulating layer to form a through cavity; the middle-frequency piezoelectric layer, the high-frequency piezoelectric layer and the high-frequency matching layer are sequentially arranged in the penetrating cavity from bottom to top. Each piezoelectric layer of the stacked ultrasonic transducer can be excited to generate ultrasonic waves with different frequencies, and the ultrasonic waves generated by the piezoelectric layers are spatially superposed, so that unipolar ultrasonic pulses are generated to improve the imaging quality, and meanwhile, the occupied area is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a stacked ultrasonic transducer according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an apparatus for generating short-period unipolar pulses based on a stacked ultrasonic transducer according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a waveform of a low frequency ultrasonic wave excited by a low frequency piezoelectric layer at 1MHz according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a waveform of an intermediate frequency ultrasonic wave excited by an intermediate frequency piezoelectric layer at 3MHz according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of waveforms of high-frequency ultrasonic waves excited by the high-frequency piezoelectric layer at 6MHz according to the embodiment of the present invention;
fig. 6 is a schematic view of a monopole ultrasonic waveform excited by the stacked ultrasonic transducer according to the embodiment of the present invention.
Description of the symbols: 1-backing layer, 2-low frequency piezoelectric layer, 3-insulating layer, 4-medium frequency piezoelectric layer, 5-high frequency piezoelectric layer, 6-low frequency matching layer, 7-high frequency matching layer, 8-stacked ultrasonic transducer, 9-hydrophone.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a stacked ultrasonic transducer, aims to generate short-period unipolar ultrasonic pulses to improve imaging effect and reduce floor area, and can be applied to the technical field of medical ultrasonic detection instruments. According to the stacked ultrasonic transducer disclosed by the invention, each piezoelectric layer can be excited to generate ultrasonic waves with different frequencies, and the ultrasonic waves generated by each piezoelectric layer are spatially superposed, so that a unipolar ultrasonic pulse is generated to improve the imaging effect, and meanwhile, the occupied area is reduced.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic structural diagram of a stacked ultrasonic transducer according to an embodiment of the present invention. As shown in fig. 1, the stacked ultrasonic transducer in this embodiment includes a backing layer 1, a low-frequency piezoelectric layer 2, an insulating layer 3, and a combination layer sequentially arranged from bottom to top; the combined layer includes: a low frequency matching layer 6, a medium frequency piezoelectric layer 4, a high frequency piezoelectric layer 5, and a high frequency matching layer 7.
The low-frequency matching layer 6 is arranged on the upper surface of the insulating layer 3; etching the upper surface of the low-frequency matching layer 6 downwards to the upper surface of the insulating layer 3 to form a through cavity; the middle-frequency piezoelectric layer 4, the high-frequency piezoelectric layer 5 and the high-frequency matching layer 7 are sequentially arranged in the through cavity from bottom to top.
The low-frequency piezoelectric layer 2 is used for receiving a low-frequency excitation signal and generating low-frequency ultrasonic waves; the intermediate frequency piezoelectric layer 4 is used for receiving an intermediate frequency excitation signal and generating intermediate frequency ultrasonic waves; the high-frequency piezoelectric layer 5 is used for receiving a high-frequency excitation signal and generating high-frequency ultrasonic waves.
The low-frequency matching layer 6 is used for reinforcing the forward wave of the low-frequency ultrasonic wave and improving the penetration efficiency and the relative bandwidth of the low-frequency ultrasonic wave; the high-frequency matching layer 7 is used for reinforcing the forward wave of the high-frequency ultrasonic wave and improving the penetration efficiency and the relative bandwidth of the high-frequency ultrasonic wave; the high-layer matching layer and the high-frequency piezoelectric layer 5 form a medium-frequency matching layer, and the medium-frequency matching layer is used for reinforcing the forward wave of the medium-frequency ultrasonic wave and improving the penetration efficiency and the relative bandwidth of the medium-frequency ultrasonic wave; the forward wave is an ultrasonic wave transmitted from the backing layer 1 to the high-frequency matching layer 7.
The backing layer 1 is used for attenuating the backward wave of the low-frequency ultrasonic wave, the backward wave of the medium-frequency ultrasonic wave and the backward wave of the high-frequency ultrasonic wave; the backward wave is a backward wave of the forward wave.
The insulating layer 3 is made of a high voltage-resistant material and is used for isolating electric contact between the low-frequency piezoelectric layer 2 and the medium-frequency piezoelectric layer 4 and reducing electric interference.
The forward wave of the low-frequency ultrasonic wave, the forward wave of the medium-frequency ultrasonic wave and the forward wave of the high-frequency ultrasonic wave are superposed to form a monopole ultrasonic wave.
Optionally, the acoustic impedances of the low frequency piezoelectric layer 2, the medium frequency piezoelectric layer 4 and the high frequency piezoelectric layer 5 are the same.
Optionally, the ratio of the acoustic impedance of the backing layer 1 to the acoustic impedance of the low frequency piezoelectric layer 2 ranges from 0.6:1 to 1.2:1, with a ratio closer to 1 being better; the thickness of the backing layer 1 is selected according to the acoustic attenuation coefficient of the material, the ultrasonic frequency and the specific application scenario.
Optionally, the acoustic impedance of the insulating layer 3 is 0.1-1.5 times that of the low frequency piezoelectric layer 2.
Optionally, the thickness of the insulating layer 3 is 0.01 to 3 times of the wavelength of the high-frequency ultrasonic wave, and the smaller the thickness is, the larger the difference between the acoustic impedance of the selected material and the acoustic impedance of the low-frequency piezoelectric layer 2 is.
Optionally, the material of the low-frequency piezoelectric layer 2 is piezoelectric ceramic, piezoelectric single crystal and/or piezoelectric composite material; the medium-frequency piezoelectric layer 4 is made of piezoelectric ceramics, piezoelectric single crystals and/or piezoelectric composite materials; the material of the high-frequency piezoelectric layer 5 is piezoelectric ceramic, piezoelectric single crystal and/or piezoelectric composite material.
Optionally, the center frequency of the low-frequency ultrasonic wave is 1MHz-10 MHz; the central frequency of the medium-frequency ultrasonic wave is 2MHz-40MHz, and the central frequency of the medium-frequency ultrasonic wave is 2-4 times of the central frequency of the low-frequency ultrasonic wave; the center frequency of the high-frequency ultrasonic wave is 4MHz-100MHz, and the center frequency of the high-frequency ultrasonic wave is 2-4 times of the center frequency of the medium-frequency ultrasonic wave.
Optionally, the low-frequency matching layer 6 is a single-layer structure made of a single material or a multi-layer structure made of multiple different materials; the high-frequency matching layer 7 is a single-layer structure composed of a single material or a multi-layer structure composed of a plurality of different materials.
Optionally, the thickness of the low-frequency matching layer 6 is 0.1 to 0.5 times of the wavelength of the low-frequency matching ultrasonic wave; the low-frequency matching ultrasonic wave is the ultrasonic wave when the low-frequency ultrasonic wave is transmitted to the low-frequency matching layer 6; the thickness of the high-frequency matching layer 7 is 0.1-0.5 times of the wavelength of the high-frequency matching ultrasonic wave; the high-frequency matching ultrasonic wave is an ultrasonic wave when the high-frequency ultrasonic wave is transmitted to the high-frequency matching layer 7. Optionally, the widths of the low-frequency piezoelectric layer 2, the medium-frequency piezoelectric layer 4, the high-frequency piezoelectric layer 5, the low-frequency matching layer 6, the high-frequency matching layer 7, the insulating layer 3 and the backing layer 1 are consistent; the length ratio of the high-frequency piezoelectric layer 5 to the medium-frequency piezoelectric layer 4 is 1:1-1:2, and the length ratio of the medium-frequency piezoelectric layer 4 to the low-frequency piezoelectric layer 2 is 1:1.2-1: 3.
Fig. 2 is a schematic diagram of an apparatus for generating short-period unipolar pulses based on a stacked ultrasonic transducer according to an embodiment of the present invention. As shown in fig. 2, the device for generating short-period unipolar pulses based on the stacked ultrasonic transducer in this embodiment includes a multi-channel signal generator, a stacked ultrasonic transducer 8, a hydrophone 9, a signal collector, and a signal processing unit, which are connected in sequence. The steps of using the device to generate monopole ultrasound are as follows:
(1) the multi-channel signal generator generates a low-frequency excitation signal, the low-frequency excitation signal is a sine wave with a single period of 1MHz, and the burst period is set to be 1 kHz.
(2) The low frequency piezoelectric layer 2 having a center frequency of 1MHz is excited with a low frequency excitation signal, and the low frequency piezoelectric layer 2 generates low frequency ultrasonic waves as shown in fig. 3.
(3) The hydrophone 9 receives low frequency ultrasound.
(4) The signal collector collects signals received by the hydrophone 9.
(5) The signal processing unit displays the waveform shape of the signal collected by the signal collector and the time when the peak value appears.
(6) The multi-channel signal generator generates an intermediate frequency excitation signal, the intermediate frequency excitation signal is a sine wave with a single period of 3MHz, and the burst period is set to be 1 kHz.
(7) The medium frequency piezoelectric layer 4 having a center frequency of 3MHz is excited with a medium frequency excitation signal, as shown in fig. 4, and the medium frequency piezoelectric layer 4 generates medium frequency ultrasonic waves.
(8) The hydrophone 9 receives the medium frequency ultrasonic waves.
(9) And (5) repeating the steps (4) to (5).
(10) The multi-channel signal generator generates a high-frequency excitation signal, the high-frequency excitation signal is a sine wave with a single period of 6MHz, and the burst period is set to be 1 kHz.
(11) The high-frequency piezoelectric layer 4 having a center frequency of 6MHz is excited with a high-frequency excitation signal, and as shown in fig. 5, the high-frequency piezoelectric layer 4 generates high-frequency ultrasonic waves.
(12) The hydrophone 9 receives high frequency ultrasound.
(13) And (5) repeating the steps (4) to (5).
(14) And calculating the time difference according to the time of the peak value of the three signals with different frequencies, and debugging the voltage proportion excited by the multipath signal generator.
(15) According to the time difference, a low-frequency excitation signal excites the low-frequency piezoelectric layer 2 to generate low-frequency ultrasonic waves, when the forward waves of the low-frequency ultrasonic waves reach the upper surface of the medium-frequency piezoelectric layer 4, the medium-frequency excitation signal excites the medium-frequency piezoelectric layer 4 to generate medium-frequency ultrasonic waves, and according to the wave superposition principle, the forward waves of the low-frequency ultrasonic waves 2 and the forward waves of the medium-frequency ultrasonic waves 4 are synthesized into first ultrasonic waves; when the first ultrasonic wave reaches the upper surface of the high-frequency piezoelectric layer 5, the high-frequency excitation signal excites the high-frequency piezoelectric layer 5 to generate a high-frequency ultrasonic wave, and the forward waves of the first ultrasonic wave and the high-frequency ultrasonic wave are synthesized into a monopole ultrasonic wave according to the wave superposition principle, and the backward wave of each ultrasonic wave is attenuated to zero at the backing layer 1. The forward wave is ultrasonic wave transmitted from the backing layer to the high-frequency matching layer, and the backward wave is ultrasonic wave in the direction opposite to the forward wave.
(16) The hydrophones receive and record monopole ultrasound waves.
(17) The signal processing unit processes the monopole ultrasound, including but not limited to filtering, fourier transforms, and various leading edge algorithms, to image and calculate bandwidth, and the waveform of the monopole ultrasound is shown in fig. 6.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (9)
1. A stack ultrasonic transducer is characterized by comprising a back lining layer, a low-frequency piezoelectric layer, an insulating layer and a combined layer which are sequentially arranged from bottom to top; the combined layer includes: the piezoelectric device comprises a low-frequency matching layer, a medium-frequency piezoelectric layer, a high-frequency piezoelectric layer and a high-frequency matching layer;
the upper surface of the insulating layer is provided with the low-frequency matching layer; etching the upper surface of the low-frequency matching layer downwards to the upper surface of the insulating layer to form a through cavity; the medium-frequency piezoelectric layer, the high-frequency piezoelectric layer and the high-frequency matching layer are sequentially arranged in the penetrating cavity from bottom to top;
the low-frequency piezoelectric layer is used for receiving a low-frequency excitation signal and generating low-frequency ultrasonic waves; the medium-frequency piezoelectric layer is used for receiving medium-frequency excitation signals and generating medium-frequency ultrasonic waves; the high-frequency piezoelectric layer is used for receiving a high-frequency excitation signal and generating high-frequency ultrasonic waves;
the low-frequency matching layer is used for reinforcing the forward wave of the low-frequency ultrasonic wave; the high-frequency matching layer is used for reinforcing the forward wave of the high-frequency ultrasonic wave; the high-frequency matching layer and the high-frequency piezoelectric layer form a medium-frequency matching layer, and the medium-frequency matching layer is used for reinforcing the forward wave of the medium-frequency ultrasonic wave; the forward wave is an ultrasonic wave transmitted from the backing layer to the high-frequency matching layer;
the backing layer is used for attenuating the back waves of the low-frequency ultrasonic waves, the back waves of the medium-frequency piezoelectric layer and the back waves of the high-frequency ultrasonic waves; the backward wave is a backward wave of the forward wave;
the forward wave of the low-frequency ultrasonic wave, the forward wave of the medium-frequency ultrasonic wave and the forward wave of the high-frequency ultrasonic wave are superposed to form a monopole ultrasonic wave.
2. The stacked ultrasonic transducer of claim 1, wherein the acoustic impedances of the low frequency piezoelectric layer, the medium frequency piezoelectric layer, and the high frequency piezoelectric layer are the same.
3. The stacked ultrasonic transducer of claim 1, wherein a ratio of the acoustic impedance of the backing layer to the acoustic impedance of the low frequency piezoelectric layer is in a range of 0.6:1-1.2: 1.
4. The stacked ultrasonic transducer of claim 1, wherein the acoustic impedance of the insulating layer is 0.1-1.5 times the acoustic impedance of the low frequency piezoelectric layer.
5. The stacked ultrasonic transducer according to claim 1, wherein the thickness of the insulating layer is 0.01 to 0.1 times the wavelength of the high-frequency ultrasonic waves.
6. The stacked ultrasonic transducer according to claim 1, wherein the material of the low frequency piezoelectric layer is a piezoelectric ceramic, a piezoelectric single crystal and/or a piezoelectric composite material; the medium-frequency piezoelectric layer is made of piezoelectric ceramics, piezoelectric single crystals and/or piezoelectric composite materials; the material of the high-frequency piezoelectric layer is piezoelectric ceramic, piezoelectric single crystal and/or piezoelectric composite material.
7. The stacked ultrasonic transducer according to claim 1, wherein the center frequency of the low-frequency ultrasonic waves is 1MHz-10 MHz; the central frequency of the medium-frequency ultrasonic wave is 2MHz-40MHz, and the central frequency of the medium-frequency ultrasonic wave is 2-4 times of the central frequency of the low-frequency ultrasonic wave; the center frequency of the high-frequency ultrasonic wave is 4MHz-100MHz, and the center frequency of the high-frequency ultrasonic wave is 2-4 times of the center frequency of the medium-frequency ultrasonic wave.
8. The stacked ultrasonic transducer according to claim 1, wherein the low frequency matching layer is a single layer structure composed of a single material or a multilayer structure composed of a plurality of different materials; the high-frequency matching layer is of a single-layer structure formed by adopting a single material or a multi-layer structure formed by adopting a plurality of different materials.
9. The stacked ultrasonic transducer according to claim 1, wherein the thickness of the low frequency matching layer is 0.1-0.5 times the wavelength of the low frequency matching ultrasonic wave; the low-frequency matching ultrasonic wave is the ultrasonic wave when the low-frequency ultrasonic wave is transmitted to the low-frequency matching layer;
the thickness of the high-frequency matching layer is 0.1-0.5 times of the wavelength of the high-frequency matching ultrasonic wave; the high-frequency matching ultrasonic wave is the ultrasonic wave when the high-frequency ultrasonic wave is transmitted to the high-frequency matching layer.
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| TW200815112A (en) * | 2006-09-18 | 2008-04-01 | Univ Nat Cheng Kung | Transducer |
| JP2009105331A (en) * | 2007-10-25 | 2009-05-14 | Panasonic Corp | Piezoelectric thin-film element |
| CN104722469A (en) * | 2015-03-02 | 2015-06-24 | 深圳市理邦精密仪器股份有限公司 | Ultrasonic transducer and manufacturing method thereof |
| CN106449966A (en) * | 2016-11-17 | 2017-02-22 | 北京钛方科技有限责任公司 | Piezoelectric sensing device and application |
| CN108734051A (en) * | 2017-04-13 | 2018-11-02 | 南昌欧菲生物识别技术有限公司 | Ultrasonic sensor and electronic device |
| CN110261486A (en) * | 2019-05-22 | 2019-09-20 | 杭州意能电力技术有限公司 | A kind of ultrasonic probe emitting multiple-frequency signal and its manufacture craft |
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